1. Field of the Invention
The present invention relates generally to orthopedic prosthetic devices. More specifically, the invention relates to a femoral orthopedic knee implant for use in conjunction with a total knee arthroplasty (xe2x80x9cTKAxe2x80x9d), wherein the femoral component is designed to accommodate a broader range of knee flexion than femoral components known in the art.
2. Description of the Related Art
Disease and trauma affecting the articular surfaces of the knee joint are commonly effectively treated by surgically replacing the articulating ends of the femur and tibia with prosthetic femoral and tibial implants, referred to as total knee replacements (xe2x80x9cTKRxe2x80x9d). These implants are made of materials that exhibit a low coefficient of friction as they articulate against one another so as to restore normal, pain free, knee function.
As a knee joint moves through a ROM, the angle of the distal femur relative to the mechanical axis of the person""s leg changes. During high flexion, this change is even more pronounced. For example, as a person""s natural knee is moved through a ROM from about 0xc2x0 to about 155xc2x0, the angle of femoral rotation about the transverse axis which is perpendicular to the mechanical axis of the person""s leg may move from about 10xc2x0 at to about 30xc2x0.
Most TKRs, however, include femoral components that are designed to accommodate knee joint articulation from a position of slight hyper extension to approximately 115xc2x0 to 130xc2x0 of flexion. However, the healthy human knee is capable of a range of motion (xe2x80x9cROM.xe2x80x9d) approaching 170xc2x0 of flexion, and a ROM in around 155xc2x0 is required for deep kneeling and squatting as may be required during some sporting, religious or cultural events.
There is a need, therefore, for an improved TKR femoral component that accommodates knee xc2x0flexion, under optimal conditions, of more than 130xc2x0 (xe2x80x9chigh flexionxe2x80x9d).
The present invention comprises, in one embodiment thereof, an improved femoral prosthesis for a TKR. The femoral component of the TKR comprises an internal non-articulating bone contacting surface adapted to receive a resected distal femur. In a preferred embodiment, the bone contacting surfaces of the femoral component include anterior, distal, and posterior chamfer surfaces, which may further comprise bone growth promoting surfaces attached thereto.
The femoral component further comprises anterior, distal, medial posterior and, lateral posterior articulating portions, referred to herein as medial and lateral posterior condyles. The medial and lateral condyles each comprise a unique xe2x80x9cheight.xe2x80x9d The height of each condyle is measured from a line tangent to the distal articulating surface to the proximal tip of a particular condyle. The differences in the medial and lateral condylar height of a prosthetic femoral component according to the present invention permit a larger angle of femoral rotation in a TKR about the mechanical axis of a patient""s leg. In addition, the extent to which the medial aspect of the lateral femoral condyle extends into the intercondylar region of the femoral prosthetic component is reduced in the present invention to accommodate high flexion.
An advantage of the present invention is that it allows greater rotation of the distal femur about a leg""s mechanical axis. This greater rotation is necessary to, and therefore accommodates, high flexion in a patient""s knee.
Other advantages and features of the present invention will be apparent to those skilled in the art upon a review of the appended claims and drawings.